Question

answer this fastly please it's urgent

Answer 1

f(x) = x² + x + 1
f (a) => a² + a + 1 = 0 (as a is a zero of f(x))
            a² = - (a+1)
          -a² = (a+1)   ---------------------------------------------------------1

f(b)=> b²+b+1 = 0 (as b is a zero of f(x))
           b² = -(b+1)
          -b² = (b+1)    --------------------------------------------------------2

(a+1)(b+1) = -a² - b²     [ by 1 and 2 ] 
                  = (-a+b)(-a-b)   [ a² - b² = (a+b)(a-b) ]


 (: Hope this helpz :)